Abstract:A modified Kalman filter is designed for the kinematic POD, which combines the advantages of the least square adjustment and the Kalman filter. Then the GRACE GPS data are processed with the modified Kalman filter, and by comparison with the GFZ’s reduced-dynamic POD, the accuracy on x, y and z directions are better than 3 cm, 4 cm, and 3.5 cm respectively. According to the performance of the new Kalman filter, we can expect that it can be used in the kinematic orbit determination for space borne GPS data with 1 Hz sampling rate in the future.